The proposed research is designed to contribute to the understanding of the neuronal circuitry in the cerebral cortex, including mechanisms for generation and termination of epileptiform activity. The experiments will be carried out on the olfactory cortex -a phylogenetically old portion of the cerebral cortex that shares features of organization with the neocortex but is much simpler in structure and easier to study. The piriform cortex, which is the largest of the olfactory cortical areas, will be studied because of its uniform, precisely-laminated structure. Three areas will be explored: a) the association fiber systen, b) inhibitory processes, and c) mechanisms of generation and termination of interictal seizure activity. Our working hypothesis with respect to the association fiber system is that it is involved in recognition of complex, spatially distributed patterns, perhaps in a fashion similar to that in higher-order neocortical areas. Several tenets of this hypothesis will be tested with intracellular recording and staining techniques. Studies of inhibitory mechanisms will concentrate on newly-discovered types of inhibitory processes. Methods to be employed include combined morphological-physiological study with intracellular techniques and both light and electron microscopic study of cells labeled with 3H-GABA and the Golgi gold-toning method. Our recent findings concerning the association and inhibitory fiber systems and preliminary studies with convulsant drugs have suggested experiments to test hypotheses concerning mechanisms for generation and restriction of interictal seizure activity. These experiments will involve intracellular recording and current source-density analysis of extracellular field potentials. The studies of neuronal circuitry should provide insights into the olfactory discrimination process and, in addition, may provide general principles of value in understanding more complex parts of the cerebral cortex. With regard to epileptogenesis, it is hoped that study of this largely unexplored part of the cerebral cortex will lead to new insights by virtue of its special structural and physiological features.